Search Results (177)

Waste biomass can serve as a feedstock to produce functionalized biochars (BCs) for phosphate removal. However, their sorption performance depends on feedstock properties, pyrolysis conditions, and modification strategy. This study compared BCs produced from tomato plant residues (Solanum lycopersicum L.; T) and shea nut shells (Vitellaria paradoxa; VP), pyrolyzed at 400 and 500 °C and modified with iron (Fe) or diatomite (DT). Their physicochemical and structural properties and phosphate sorption capacity were evaluated in a model solution and selected real wastewater matrices. Exploratory variance decomposition showed that modification type represented the largest proportion of variability in physicochemical and structural properties of 12 BC variants (59.75%), whereas feedstock type represented 84.84% of the observed variation in phosphate sorption across the 8 variants. The effect of modification was feedstock-dependent: DT was particularly beneficial for T-derived BCs, whereas Fe modification was more beneficial for VP-derived BCs. Selected magnetic BCs also removed phosphate from real wastewater matrices, although removal efficiency differed between matrices. Overall, phosphate sorption capacity could not be predicted from modification type or pyrolysis temperature alone, indicating that feedstock characteristics should be considered when selecting functionalization strategies. Full article

Macadamia is a diploid rainforest tree native to Australia. A total of 349 samples, including wild and domesticated accessions, were subjected to whole-genome sequencing, identifying 4.2 to 7.7 million, 2.4 to 7.4 million, 2.8 to 4.4 million, 1.6 to 3.2 million and 3.1 to 9.6 million single-nucleotide polymorphism (SNP) positions for M. integrifolia, M. tetraphylla, M. ternifolia, M. jansenii and the domesticated cultivars and breeding selections respectively. Overall diversity for wild M. integrifolia, M. tetraphylla, M. ternifolia and M. jansenii was 4.43%, 4.33%, 1.80% and 1.1%, respectively. Domesticated M. integrifolia showed an overall diversity of 3.4%, which was 1.03 percentage points lower than that of wild M. integrifolia. Among breeding groups, Australian breeding selections had the highest diversity, whereas Hawaiian cultivars had the lowest. Wild M. integrifolia, M. tetraphylla, M. ternifolia and M. jansenii exhibited heterozygosity ranging from 0.36% to 0.71%, 0.30% to 0.71%, 0.29% to 0.42%, and 0.19% to 0.34 respectively. Heterozygosity showed weak correlation with yield efficiency, cumulative kernel yield, and cumulative nut-in-shell yield, with a weak trend suggesting that performance may be the greatest at intermediate levels of heterozygosity. Overall, substantial genetic variation exists among the different macadamia accessions, with wild germplasm showing the greatest diversity. Full article

Walnuts are commercially important tree nuts whose moisture content (MC) influences quality, shelf life, and post-harvest processing. This study evaluated the potential of low-cost acoustic sensing combined with machine learning for non-destructive MC prediction. Sixty in-shell walnuts were subjected to controlled drying at 40 °C for 26 h, with acoustic recordings and physical measurements collected every two hours. Acoustic signals were processed using Wavelet Soft Threshold Denoising (WSTD), Short-Time Fourier Transform (STFT), and Variational Mode Decomposition (VMD), and features were extracted from the resulting signals. Predictive models included generalized linear models (GLM), random forests (RF), gradient boosting machines (GBM), and Partial Least Squares (PLS) approaches. Following grouped walnut-level validation, the highest MC prediction performance was achieved by the model combining dimensional and acoustic descriptors (RF: R² = 0.836; GBM: R² = 0.826), while the model combining drying time and acoustic descriptors achieved moderate predictive performance (RF: R² = 0.762; GBM: R² = 0.760). Overall, the results provide proof-of-concept evidence that acoustic descriptors may complement physical measurements for non-destructive walnut moisture-content prediction. However, substantially larger independent datasets collected across multiple cultivars, production batches, acquisition conditions, and external validation studies will be required before practical industrial implementation can be considered. Full article

The effects of pyrolysis temperature (400–500 °C) and time (30–90 min) on the yield and chemical and physical properties of biochar produced from almond and pistachio shells were studied using a fixed-bed pyrolyzer. Thermogravimetric analysis (TGA) was employed to characterize the kinetics of thermal degradation of the shells. This study compared the thermal behavior observed by TGA with biochar yields obtained from a fixed-bed pyrolyzer, providing insight into the agreement between laboratory-scale thermogravimetric measurements and fixed-bed pyrolysis performance. Fourier transform infrared spectroscopy (FTIR) was performed for each type of biochar. Results showed higher biochar yields from almond shells (35.0–41.3% dry basis) than from pistachio shells (26.8–36.7% dry basis). Shell type, pyrolysis temperature, pyrolysis time, and their interactions had significant effects on biochar yield. The Derivative Thermogravimetric (DTG) profiles showed distinct thermal decomposition patterns for almond and pistachio shells. Almond shells exhibited broader decomposition regions, while pistachio shells showed more distinct decomposition stages. FTIR analysis of both shell biochars indicated reduced O–H and oxygen-containing groups with increasing pyrolysis temperature and residence time, suggesting greater carbonization, aromatic enrichment, and formation of carbonaceous compounds. Greater biochar yields were obtained from the fixed-bed pyrolyzer than from TGA. A first-order kinetics model adequately described the thermal decomposition of both shell types. Apparent activation energies were 41.83–44.99 kJ mole⁻¹ for almond shells and 58.19–63.58 kJ mole⁻¹ for pistachio shells. Model validation showed a good agreement between the experimental and predicted conversion values. The results provide a basis for evaluating the potential of TGA-derived thermal behavior to inform biochar production conditions in fixed-bed pyrolysis. Full article

The transition from a linear to a circular economic model is critical for the sustainability of the Amazonian bioeconomy. Although Amazon nuts (internationally recognized as Brazil nuts, Bertholletia excelsa) represent a major natural bioresource, their production chain faces structural challenges, particularly concerning the underutilization and disposal of agro-industrial residues. This narrative review analyzes the Amazon nut market, processing technologies, and supply chain, with a specific focus on biomass valorization. By evaluating the recent literature across major scientific databases, this study maps the technological readiness and feasibility of integrating a circular economy model. We critically examine alternative technologies for transforming specific residues, particularly the woody fruit pods, hard seed shells, and oil press cakes, into value-added bioproducts. Key valorization routes discussed include protein concentrates and amino acid supplements from the press cake, cellulose nanocrystals and organic panels from the hard seed shell, biosolvents, and bioenergy/biochar generation via pyrolysis. The review concludes that while the current industry remains strictly focused on kernel commerce, transitioning toward a circular model appears technically promising, but its economic feasibility remains unconfirmed for most valorization pathways. However, successful industrial implementation requires overcoming logistical supply chain barriers and advancing the technology readiness levels of these valorization pathways. Full article

Nut quality is of great economic concern because nuts are rich in oil, which can be rapidly oxidised if the nuts are not properly handled. Tree nuts are often maintained in-shell after harvest so that they can be processed later and marketed out of season. Poor handling procedures prior to kernel storage, and suboptimal temperatures during storage, may compromise quality and lead to colour development, particularly for tree nuts with high oil content that are susceptible to oxidative rancidity. However, there is limited information on the effects of in-shell handling procedures or kernel storage temperatures on the quality and colour development of tree nuts during long-term storage. We determined how the freezing of kernels from the tropical tree, canarium (Canarium indicum), affected their subsequent kernel quality when stored at 25 °C for up to 9 months. Pre-frozen kernels had significantly higher peroxide values than non-frozen kernels (3.90 and 0.35 meq O₂/kg oil, respectively) after 3 months of storage. However, pre-frozen kernels had significantly lower peroxide values than non-frozen kernels after 9 months of storage, most likely due to degradation of peroxides to secondary compounds over time. We also evaluated how the prolonged maintenance of nuts-in-shell prior to processing affected kernel quality, oil composition and colour development during storage at 4 °C or 25 °C for up to 15 months. Storage at 25 °C led to higher free fatty acid levels from 9 months onwards than storage at 4 °C, both for the kernels that had been maintained previously in-shell and for the fresh kernels. Nonetheless, peroxide values and free fatty acid levels of the previously stored in-shell and of the fresh kernels were still below the acceptable quality limits for tree nuts. The concentrations of palmitic, stearic and linoleic acid in fresh kernels stored at 4 °C or 25 °C did not differ between the storage temperatures. However, the oleic acid concentration was higher in refrigerated kernels than unrefrigerated kernels. Kernels stored in-shell had lower reflectance at 25 °C than those stored at 4 °C at 12 months of storage. Our findings demonstrate that freezing of canarium kernels accelerates lipid oxidation and quality loss, but that refrigeration suppresses lipid oxidation. Kernels stored at room temperature were still below the maximum acceptable limits for peroxide values and free fatty acid levels, although they would likely develop rancidity if stored for more than 15 months. We recommend that the kernels of tropical tree nuts with high oil content like canarium not be frozen, but should be freshly processed, kept at 4 °C if shelled, and stored immediately, to ensure high quality. Full article

This study investigated the adsorption of pharmaceutical formulations (aspirin, enantyum, ibuprofen, metamizol, nolotil, paracetamol, and termalgin) and simultaneous binary mixtures of them onto activated carbons derived from olive stone (OSPC) and pine nut shell (PNSPC). Both biocarbons exhibited superior properties without prior washing, exhibiting the highest adsorption capacity (45 mg/g) with 1.0 g OSPC/L and 50 mg ENA/L at pH 2. FTIR analysis identified oxygenated and phosphate-related surface groups in both carbons, with OSPC exhibiting stronger functionalization, and revealed minimal differences in adsorption between commercial formulations and pure active ingredients. Raman spectroscopy showed small increases in the I_D/I_G ratio after adsorption, attributed to slight increases in defect density, without significantly altering the carbon structure. SEM analysis revealed that OSPC exhibited a more heterogeneous and porous structure than PNSPC, consistent with its larger BET surface area. The presence of surface phosphate groups was detected using XRD, and they were found to be more pronounced in OSPC; this was attributed to the fact that the adsorbents were not washed beforehand. Finally, OSPC was used to adsorb each of the six drugs independently in 14–15 consecutive cycles, with removal efficiency exceeding 85%; thus, its use could be considered in the treatment of wastewater containing the drugs from this study, in line with the circular economy, which aims to achieve zero waste. Full article

The sustainable management of almond (Prunus dulcis) hulls and shells represents a major challenge for the global almond industry. Although almond hulls possess considerable nutritional value and can be used as livestock feed, concerns about pesticide residues limit their utilisation and pose environmental and economic disposal challenges. Therefore, alternative crop protection strategies that reduce reliance on chemical pesticides while maintaining productivity are required. Silicon has been widely reported to enhance plant resistance against biotic and abiotic stresses, improve nutrient utilisation, and increase crop productivity. This study evaluated the effects of an enhanced potassium silicate formulation applied through fertigation on pest and disease incidence, plant performance, and kernel yield in a commercial almond orchard over two consecutive growing seasons. The formulation contained potassium silicate (50% w/v), amino acids (42% w/v), Complex Polymeric Poly-Hydroxy Acid (CPPA) (1.5% w/v), and water. Treatments were applied twice per season at a rate of 30 L ha⁻¹ and compared with a grower-standard management program. Silicon-treated trees exhibited significantly lower levels of microbial disease damage in both leaves and mature nuts compared with untreated controls. Across the two growing seasons, pest- and disease-related damage to nuts was reduced by up to 59%. Silicon treatment also resulted in substantial increases in oven-dried kernel weight, ranging from 19% to 33% across the evaluated almond varieties. No adverse effects were observed on flower-to-nut conversion, chlorophyll content, kernel nutritional quality, or leaf nutrient status. The findings demonstrate that enhanced potassium silicate fertigation can improve pest and disease resistance while increasing kernel yield in commercial almond production systems. The technology offers a promising strategy for reducing reliance on chemical pesticides and supporting the sustainable utilisation of almond by-products, including their use in livestock feed and bioenergy production. Full article

The study investigated and quantified the feasibility of using waste derived from shea tree fruit shells (Vitellaria paradoxa) as an organic multifunctional additive for building ceramic bodies, focusing on its influence on thermal behavior, pore formation, and mechanical performance. The scope of the research included sieve analysis, chemical analysis (WDXRF), phase composition analysis (XRD), thermal analysis coupled with evolved gas analysis (DTA–TG–EGA), and the evaluation of the physical and mechanical properties of the obtained ceramic materials. The analyses demonstrated that the shea waste was characterized by a high content of organic matter, a loss in ignition of 93.84%, and a calorific value of 19.421 kJ/g. The incorporation of biomass resulted in increased porosity and reduced apparent density of the ceramic materials. The relative porosity increased from 27.00% for the reference sample to 34.98% for the sample containing 30% shea waste. Simultaneously, the compressive strength decreased from 23.67 MPa to 10.10 MPa, while the flexural strength decreased from 8.96 MPa to 4.76 MPa. Partial replacement of conventional mineral additives and, in particular, partial substitution of fossil-derived kiln fuel demand with high-calorific biomass enabled a reduction in overall CO₂ emissions associated with ceramic production. This includes both process-related emissions from raw material decomposition and fuel-related emissions generated in the tunnel kiln. In addition, a reduced contribution of carbon originating from inorganic mineral sources (including carbonates) to total emissions covered by emission trading systems (ETSs) was observed. Despite the reduction in mechanical parameters, samples containing up to 20% shea waste retained properties suitable for application in the production of ceramic building materials. Full article

Compost derived from macadamia husks provides a sustainable alternative for improving soil fertility, nutrient uptake, and crop productivity. This study evaluated the effects of different macadamia husk compost (MHC) application rates on nut yield, nut quality, and leaf nutrient concentration in macadamia trees. Compost application significantly (p < 0.05) increased leaf potassium (K), magnesium (Mg), and zinc (Zn) concentrations, with the highest values recorded at 12 t ha⁻¹. Other nutrients (N, P, Ca, Cu, Mn, Fe, and B) were not significantly affected. Nut yield increased with compost application, with the highest yield observed at 12 t ha⁻¹ (63.10 kg tree⁻¹), followed by 8 t ha⁻¹, 4 t ha⁻¹, and the control. Similarly, nut-in-shell yield improved with increasing compost rates. Compost application enhanced key nut quality parameters, including sound kernel recovery, total kernel recovery, and first grade nuts, while maintaining insect damage and immature nuts within acceptable industry standards. Overall, nut quality improved in 2022 compared to 2021. These findings demonstrate that macadamia husk compost is an effective organic amendment for improving yield, nut quality, and selected leaf nutrient concentrations, contributing to sustainable macadamia production. Full article

Anaerobic digestion (AD) of lignocellulosic biomass is often constrained by biomass recalcitrance, limiting methane recovery. This study investigated whether low-temperature dilute-acid hydrothermal pretreatment could enhance methane production from pine nut shells (PNSs), a lignin-rich and underutilized agro-industrial residue, and whether derivative-based kinetic landmarks could provide a more systematic characterization of batch AD performance. Methane production was significantly improved by dilute sulfuric acid and hydrothermal pretreatments. The highest methane yield (201.8 mL CH₄ g⁻¹ VS) was achieved under the combined 100 °C hydrothermal and 2.5% H₂SO₄ condition, representing approximately 1.8-fold and 3.3-fold increases compared with hydrothermal-only and untreated PNSs, respectively. Enhanced performance was attributed to hemicellulose solubilization, lignin disruption, and improved substrate accessibility. In contrast, excessive acid severity resulted in process instability, associated with total volatile fatty acid accumulation and pH reduction. The Modified Logistic Model (MLM) was further used to derive five kinetic landmarks (PAA, PAM, PI, PDM, and PDA) describing phase-specific features of cumulative methane production curves. While these landmarks provide a model-based framework for comparing batch AD kinetics, their nearly constant normalized yields primarily reflect the geometry of the fitted logistic function rather than independent biological invariants. Overall, the results identify 100 °C hydrothermal pretreatment with 2.5% H₂SO₄ as an effective moderate-severity strategy for enhancing methane recovery from PNSs and demonstrate the utility of MLM-derived landmarks as comparative descriptors of phase-resolved methane production. Full article

Fruit endocarp and seed coat are essential protective structures that influence key agronomic and mechanical traits in species with lignified protective tissues, yet their regulatory mechanisms remain incompletely understood. Here, we conducted a comprehensive genome-wide analysis of the MADS-box gene family in four angiosperm species: Juglans sigillata, Carya illinoinensis, Macadamia integrifolia, and Ricinus communis. A total of 58, 55, 57, and 57 MADS-box genes were identified, respectively, and systematically characterized through phylogenetic, structural, and evolutionary analyses. Comparative results revealed that MIKCc-type genes are highly conserved and primarily expanded via segmental duplication under strong purifying selection. Co-expression network analysis identified MADS-box genes as high-connectivity hub candidates that are strongly associated with genes involved in tissue specification, hormone signaling, and secondary cell wall biosynthesis. Promoters analysis indicated that these genes contain diverse cis-regulatory elements; however, these results are based on sequence prediction and do not demonstrate functional regulatory interactions. Across species, MADS-box genes exhibited analogous temporal expression dynamics during lignified endocarp and seed coat development, consistent with a potentially conserved transcriptional framework. Collectively, this study provides new insights into the evolutionary diversification and putative functions of MADS-box genes, and proposes a putative hierarchical regulatory framework for lignified endocarp and seed coat development. These findings supply valuable candidate target genes for future molecular breeding aimed at improving shell thickness, hardness, and related agronomic traits in woody nut and oilseed species. Full article

The growth of pistachio (Pistacia spp.) production, particularly in America, Iran, and Turkey, has resulted in the production of substantial quantities of by-products, including shells, fruit husks, leaves, resins, and tree pruning waste. Although these fractions contain a range of beneficial secondary compounds, they are rarely used. Recent advances in nanotechnology and materials engineering suggest that they can be used as inexpensive, renewable raw materials in the fields of agriculture, the food industry, cosmetics, pharmaceuticals, and environmental engineering. Pistachio by-products have been shown to exhibit antioxidant, antibacterial, antifungal, and anticorrosive properties, making them good candidates for use in active packaging systems and nanoencapsulation. They may also be valuable as fertilisers, animal feed, and composite materials. They have been found to have potential roles in industrial pollutant removal and energy storage, and as ‘green’ precursors for nanomaterials. This review summarises the current knowledge on the multifunctional applications of Pistacia spp. by-products, emphasising their importance in implementing circular economic strategies and sustainable industrial development. This study also addresses the practical application of pistachio by-products, as well as the widely appreciated nuts, within the domain of patents, thereby illustrating the prospective pathway of currently emerging solutions in the context of sustainable development. Full article

The growing environmental impacts associated with conventional plastics and textiles have intensified interest in bio-based and circular material alternatives. This study presents a qualitative and structured literature review of the valorization of fruit and nut agricultural residues as sustainable feedstocks for biomaterials and biotextiles, with a strategic focus on Greece. Drawing on international literature, regional agricultural production data, and validated processing technologies, the review synthesizes existing evidence on residue availability, conversion routes, environmental performance, and market trends. The reviewed literature indicates that residues such as grape pomace, olive by-products, citrus peels, and nut shells have been widely reported as suitable sources of cellulose, lignin, and pectin for the development of fibers, films, and composite materials. Findings from published life cycle assessment (LCA) studies suggest potential reductions in water use, greenhouse gas emissions, and land-use intensity compared with conventional cotton and synthetic textiles, although results vary depending on system boundaries and processing conditions. The review further highlights enabling factors, technical limitations, and policy considerations relevant to the Greek context. This study provides a qualitative integrative perspective on the opportunities and constraints associated with agricultural residue valorization, identifying key research gaps and strategic directions for future development within Greece and similar Mediterranean regions. Full article

Research is needed to improve walnut drying throughput and energy consumption in hulling plants, but current methods for sampling nuts in commercial drying bins and measuring nut moisture content limit the capacity to investigate the drying process thoroughly. A novel apparatus for obtaining walnut samples at multiple depths and locations in stadium drying bins and a novel rapid method for accurately determining walnut in-shell moisture content were developed. A second rapid moisture measurement method involving near-infrared light (NIR) was also investigated. The sampling apparatus consisted of three sampling columns installed in each walnut drying bin. Each column had gate valves at four elevations, admitting approximately 30 in-shell walnuts to rectangular buckets hanging on a cable just below each gate valve. To collect samples, the gates were opened and closed, the buckets were withdrawn, the nut samples were collected and sealed in labeled bags, and then the buckets were returned to the column to be ready for the next sampling interval. This configuration, sampling nuts at four levels across three locations in the drying bin, allowed better moisture content variability investigation during in-bin walnut drying. The rapid moisture content measurement method consisted of selecting twelve representative in-shell walnuts from each sample and grinding them in a mill. Twelve grams were sub-sampled from the well-mixed ground material and dried in an oven at 105 ± 1 °C for 3 h, then reweighed to determine moisture loss. The coefficient of variation for sub-samples within an individual sample (n = 4) averaged 2.65% for moisture contents ranging from 6% to 47% dry basis. The rapid moisture content measurement method reduced the drying time from 24 h to 3 h compared to conventional oven drying method, with an accuracy of ±0.5 to 1.5% of the full moisture content range. The best correlation observed between the NIR methodology and the rapid moisture content method was 0.74 R². These new in-bin walnut sampling and moisture-content measurement methods will accelerate future research aimed at improving walnut drying at commercial huller facilities. Full article